Conjugated aromatic polyazomethine compounds have been known for many years, and their properties and methods of preparation have been discussed in a review article (G. F. D'Alelio, Encycl. Polym. Sci. Technol., 1969, Vol. 10, pp. 659-670). Polyazomethines are typically high melting and extremely insoluble in organic solvents; they do dissolve in concentrated sulfuric acid, but solution is accompanied by decomposition.
Morgan et al. (Macromolecules 1987, Vol. 20, pp. 729-739) report that melting points of polymeric azomethines can be lowered by unsymmetrical substitution of the aromatic rings, and Wojtkowski (Macromolecules, 1987, Vol. 20, pp. 740-748) reports linking the aromatic rings with ether groups to achieve a similar result. These compounds, however, are still insoluble in common organic solvents and in the molten state are susceptible to continuing polymerization.
Introduction of long (8-18 carbon atoms) alkoxy groups into the aromatic nuclei of polyazomethines is reported (K. S. Lee et al., Makromol. Chem. 1989, Vol. 190, pp. 1547-1552) to produce polymers that are soluble in various organic solvents. However, another report (B. A. Reinhardt et al. Polym. Prepr., 1990, Vol. 31, No. 1, pp. 620-621) on polymers of similar structure describes them as soluble in methanesulfonic acid but insoluble or partially soluble in ordinary organic solvents.
U.S. Pat. Nos. 4,048,148 and 4,122,070 disclose fibers or films produced from melt-spinnable polymeric azomethine compounds having polymer melt temperatures below 375.degree. C. Because these polymers can continue to polymerize at the high temperatures of the molten state, the use of end-capping or chain-terminating agents is proposed to control the resulting changes in moleculer weight.
The utilization of aromatic polyazomethine compounds as described in the above literature and patents is limited by their high melting points, extremely poor solubility, and instability at high temperatures. The tractability of these compounds is enhanced in accordance with the invention, thereby providing improved compositions and materials that facilitate processing and fabrication of fibers and films and devices utilizing same, especially improved optical, dielectric, and semiconductor materials and devices.